Since many plants and plant parts are of economic importance to people, people have learned to manipulate the life cycle of plants for their own purposes. Various chemical and biological agents are used on commercially grown fruits and vegetables to control the timing of fruit and vegetable ripening. Some agents are used to synchronize the ripening of fruits and vegetables to assist in efficient harvesting of fruits and vegetables from the field. Other agents are used to inhibit fruit drop so that fruits remain on the plant or tree until the appropriate ripening time period. Another purpose of fruit and vegetable ripening agents is to enhance color development in a fruit or vegetable so that the fruit or vegetable has a better and more uniform color as expected by retail consumers of the fruit or vegetable. In the United States, it is current practice for many types of fruits and vegetables to be treated with one or more such agents during the growing season and after harvest. However, many of these ripening agents also cause fruits and vegetables to soften leading to a very poor storage and shelf life. An example of a ripening agent is ethephon, sold in many commercial formulations, which is used to accelerate the ripening of certain fruits, even though it simultaneously negatively impacts fruit quality. In addition, many of these agents are synthetic and have toxicological and environmental concerns such that they are not viewed favorably by fruit and vegetable consumers.
Another class of agents that is of great interest to the plant industry is the class that has senescence retardation activity. These agents can prolong the shelf life of fruits, vegetables and cut flowers. However, the timing of application of such agents can be critical to avoid unripened or immature fruit. An example of an agent used to prolong shelf life is 1-methyl cyclopropene or MCP, which is commonly used to prolong the shelf life of picked fruit. Similar to the ripening agents, many of the senescence retardation agents have toxicological and environmental concerns.
Certain members of the N-acylethanolamine (NAE) family are other examples of agents that have senescence retardation activities. Chapman, K. D. et al. (WO01/30143 (2001)) demonstrated that certain NAEs could be used to prolong the shelf life of cut flowers. Dr. Chapman speculated that in consistence with the senescence retardation activity, these NAEs may also possess the ability to slow down the ripening process in plant parts (http://www.kmsb.com/homegarden/house/flowers.448955.html), as do other senescence retardation agents.
In the recent years, naturally derived materials with good ripening and senescence retardation effects have been identified. For example, certain phospholipids (such as lysophosphatidylethanolamine (LPE) and lysophosphatidylinositol (LPI)) have been shown to accelerate fruit ripening, enhance fruit stability during storage, and increase the shelf life of plant parts by retarding senescence of plant tissues. Farag, K. M. et al., Physiol. Plant, 87:515–524 (1993); Farag, K. M. et al., HortTech., 3:62–65 (1993); Kaur, N., et al., HortScience, 32:888–890 (1997); Ryu, S. B., et al., Proc. Natl. Acad. Sci. U.S.A., 94:12717–12721 (1997); U.S. Pat. Nos. 5,126,155 and 5,110,341; and WO 99/23889. More agents like these naturally derived materials that have both ripening enhancement and senescence retardation effects are desirable in the plant industry.